Diabetes is a common disease of the older population of the United States. Estimates of the prevalence of this disease from the National Health Interview Survey indicate that about 2.4% of the U.S. population, approximately 5.5 million Americans, consider themselves to have diabetes, impaired glucose tolerance, a state of borderline glucose metabolism, exists. Diabetes is a known risk factor for microvascular (renal, retinal and neurologic) disease and macrovascular disease (accelerated atherogenesis). The effect of these morbid conditions on American health care expenses is enormous. In an effort to identify risk factors for the development of diabetes, and identify potential areas for intervention, 25 years of longitudinal data from the Baltimore Longitudinal Study of Aging are being examined. According to the report of the National Diabetes Data Group (1979) a fasting glucose of 140 mg/dl or more is diagnostic of diabetes while a fasting glucose less than 115 mg/dl is defined as normal. The range 115- 139 mg/dl is variously defined as "highly suspicious" and "probable diabetes". There is little evidence in the literature concerning the risk of morbidity or mortality in this intermediate range. Results: Fasting glucose levels as low as 103-106 mg/dl in men 28-59 years of age and 107-111 mg/dl in men 60-96 carry increased risk for the future development of diabetes. Increasing obesity and abdominal fat deposition, explain much of the increased risk for diabetes with aging. Of importance, other studies have shown that diet plus moderate exercise can decrease the obesity and abdominal fat deposition seen with aging. These results suggest that simple, safe, non-pharmacologic interventions can reduce the risk of diabetes. An additional study, utilizing the results of oral glucose tolerance testing is underway.